His announcement could open the way for a return by Nigel Farage, who quit as leader to concentrate on his failed attempt to oust Commons Speaker John Bercow from Parliament at the general election.

Lord Pearson said: "I took over as leader of Ukip last year to see the party through the General Election, and said I would then consider my position.

"We increased our vote by 50% and have many exciting plans for the future. But I have learnt that I am not much good at party politics, which I do not enjoy. I am also 68 and need to give more time to my wider interests.

"So it is right that I should stand down on September 2, early in the Parliament, to give a younger leader time to be established before the next election, which may come sooner than we think. There is no shortage of talent in Ukip, and the new leader will have my full support."

Mr Farage, who suffered serious injuries in a plane crash on polling day, did not rule out standing for the leadership again.

In an interview broadcast on BBC Radio 4's Today programme, Mr Farage said he would have to decide whether he had recovered sufficiently to take the helm of the party again.

He added: "I hadn't really considered this until a few hours ago when (Lord) Malcolm (Pearson) told me of his decision. I'm not going to say I'm absolutely not going to do the job again, but I've got to decide in the wake of that accident whether I'm strong enough to take the job on."